Sql的一些概念

DDL: Data Definition Language ,deals with object definitions and includes statements such as CREATE, ALTER, and DROP.

DML : Data Manipulation Language ,allows you to query and modify data and includes statements such as SELECT, INSERT, UPDATE, DELETE, and MERGE.

DCL : Data Control Language ,deals with permissions and includes statements such as GRANT and REVOKE.

OLTP : OnLine Transactional Processing system .

Data Warehouse : A data warehouse (DW) is an environment designed for data retrieval/reporting purposes. When serving an entire organization such an environment is called a data warehouse; when serving part of the organization (such as a specific department) it is called a data mart .

OLAP : OnLine Analytical Processing,support dynamic, online analysis of aggregated data.Online dynamic analysis of aggregated data usually involves frequent requests for different levels of aggregations, which require slicing and dicing the data. Each such request might end up being very expensive if it needs to scan and aggregate large amounts of data, and chances are the response time will not be satisfactory.